The invention is based on a system for transferring a control position of a set-point transducer to a control position of a control element that determines an output of a drive machine, as defined hereinafter.
In known systems in a machine, particularly in a vehicle, a control position of a set-point transducer should be transferred to a control position of a control element that determines an output of the driving machine by electromechanical transfer means. The electromechanical transfer means make it possible to vary the transfer. In a vehicle, the variation may for instance become necessary in order to avoid slip, or loss of traction, between the wheels driven by the driving machine and a road surface, or to keep a vehicle speed to a certain value regardless of the control position of the set-point transducer.
If the machine is a vehicle having an Otto engine as the driving machine, then the set-point transducer may for instance be connected via a Bowden cable to a gas pedal, and the control element may be connected with a throttle valve for instance, and the control position of the control element can determine an opening angle of the throttle valve.
The system furthermore includes mechanical transfer means by which the control element can be coupled to the set-point transducer, but the control element is decoupled from the set-point transducer whenever the control position of the control element corresponds to the control position of the set-point transducer. If for any reason the transfer of the control position of the set-point transducer to the control position of the control element by the electromechanical transfer means should fail, then the transfer takes place by means of the mechanical transfer means.
In a known system of this type, signals originating in the set-point transducer are transferred to an electric governor, which in turn affects the control position of a final control element that is connected to a positioning system. Between the set-point transducer and the adjusting system there is also a mechanical transfer element having a compensation element with built-in play, so that the transfer element is decoupled from the set-point transducer and/or from the final control element and/or from the adjusting system whenever the control position of the adjusting system is equivalent to the control position of the set-point transducer.
If the set-point transducer is not actuated, the control position of the adjusting system is moved by a restoring spring to a terminal position corresponding to an idling position. From the terminal position, the control position of the adjusting system can be actuated in only one adjustment direction, which represents a considerable restriction in the possibilities offered by the known system.
The compensation element of the transfer element includes a compression spring. In normal operation this compression spring is intrinsically unnecessary, unless one of the electric transfer means has failed and the adjusting system is to be coupled to the set-point transducer via the mechanical transfer element. For instance, if the compression spring has failed because of a break before this possible instance occurs, then that is not noticed until the adjusting system is to be coupled to the set-point transducer via the mechanical transfer element, but that coupling cannot be done because of the broken compression spring. This is a safety risk.